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Biodiversité Des Protistes Aquatiques: Le Paradoxe AQUAPARADOX

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Biodiversité Des Protistes Aquatiques: Le Paradoxe AQUAPARADOX Biodiversité des Protistes Aquatiques: le Paradoxe Projet ANR-07-BDIV-004 AQUAPARADOX Programme Biodiversité 2007 A IDENTIFICATION.....................................................................2 B RESUME CONSOLIDE PUBLIC B.1 Résumé Consolidé Public en Français ............................... 3 B.2 English Non-Technical Project Summary ........................... 5 C SCIENTIFIC REPORT C.1 Abstract ........................................................................ 6 C.2 Introduction .................................................................. 7 C.3 Primary Producers .......................................................... 8 C.4 Herbivores ................................................................... 10 C.5 Parasites ..................................................................... 11 C.6 Macroecology of Planktonic Protists ................................. 12 C.7 Conclusions ................................................................. 13 C.8 References .................................................................. 13 D LIST OF DELIVERABLES ........................................................ 15 E PROJET PRODUCTION E.1 Summary Table of Project Products ................................ 16 E.2 Publications, Oral Communications, Theses, Reports ......... 16 E.3 Other Project Products (software, websites) ..................... 22 E.4 Summary of Temporary Personel Employed ..................... 25 Référence du formulaire : ANR-FORM-090601-01-01 1/22 A IDENTIFICATION Acronyme du projet AQUAPAROX Titre du projet Biodiversite des Protistes Aquatiques: Le Paradoxe Coordinateur du projet John R. Dolan Microbial Ecology and (société/organisme) Biogeochemistry Group, Laboratoire d'Océanographie de Villefranche, Université Paris6 CNRS UMR 7093 Période du projet 01/08/2008 - 31/12/2011 (date de début – date de fin) Site web du projet http://www.obs-vlfr.fr/LOV/aquaparadox/ Rédacteur de ce rapport Civilité, prénom, nom M. John Dolan Téléphone 04 93 76 36 22 Adresse électronique [email protected] Date de rédaction 03/01/2012 Liste des partenaires présents à la 2. Microbial Diversity and Evolution, fin du projet (société/organisme et Ecologie, Systématique et Evolution, responsable scientifique) Université Paris-Sud XI CNRS UME 8079 Purificacion Lopez-Garcia 3. Diversity of Ocean Plankton Group, Adaptation et Diversité en Milieu Marin, Université Paris6 CNRS UMR 7144 Laure Guillou 4. Virtual Biology Laboratory, Institute of Developmental Biology and Cancer, Université Nice- Sophia Antipolis CNRS UMR 6543 Richard Christen Référence du formulaire : ANR-FORM-090601-01-01 2/22 B.1 Résumé consolidé public en français Aquaparadox: Pourquoi Autant d'Espèces dans le Plancton? Une Etude de la Biodiversité Océanique. Les plantes et animaux microscopiques du plancton forment la base de la chaîne élémentaire dans les océans. Un litre d’eau peut contenir des milliers d'espèces ce qui par extrapolation conduit à une richesse d'espèces inexpliquable dans ce monde microscopique et relativement homogène - c’est ce que l’on appelle 'le paradoxe du plancton'. Les protistes, des organismes unicellulaires, ont des caractéristiques communes : le nombre d'espèces est élevé et beaucoup semblent avoir une distribution géographique très large, voir globale. Connaître l’étendue et les raisons de cette particularité du plancton marin est essentiel pour comprendre le fonctionnement des écosystèmes océaniques et les effets du changement climatique. Nous avons examiné plusieurs questions fondamentales concernant ces organismes planctoniques en nous focalisant sur des groupes importants présentant des types fonctionnels différents : des micro-algues (des plantes), des brouteurs (des animaux) et des parasites. Y a t-il autant d'espèces que de formes morphologiques distinctes? Quel est l’influence du milieu sur la variabilité morphologique des espèces ? Certaines espèces sont-elles réellement à large distribution, ou la diversité est-elle masquée par des convergences morphologiques ? Aquaparadox était un projet de recherche fondamentale focalisé sur la biodiversité des protistes planctoniques. Sonder le plancton à travers des études des populations naturelles in situ et au laboratoire. Est-ce que les protistes et les organismes multicellulaires du plancton sont similaires en termes de distribution et de structures des populations? Nous avons examiné des populations naturelles de protistes et les avons comparées avec celles des organismes planctoniques multicellulaires les plus abondants, les copépodes. En laboratoire, nous avons étudié la variabilité des clones, issus de la même cellule. Des cultures de parasites et d’hotes ont été établies et ont permis de comprendre comment un parasite pouvait persister en infectant des hôtes typiquement saisonniers. Nous avons appliqué les outils moléculaires pour déterminer l'identité génétique des formes identifiées sur la base de leur morphologie, et évaluer le spectre d’hôtes de certains parasites. Résultats majeurs du projet. Nous avons démontré que les assemblages de protistes planctoniques ont une structure très similaire à celle des copépodes (multicellulaires) sur des échelles multiples du temps et de l'espace. Par exemple, ils ont le même gradient global de diversité: le nombre d'espèces est le plus élevé en zones tropicales, intermédiaire et zones tempérées, et minimal dans les zones polaires. Nous avons découvertes des exemples remarquables de morphologie variable parmi les protistes planctoniques (voir figure). Une espèce de Ceratium, une micro-algue, caractérisée par ses 'doigts', les résorbe à chaque coucher du soleil et les reforme à l'aube. Au moins une espèce de tintinnides est connue sous des noms différents du fait de sa capacité à fabriquer des coquilles de formes différentes. Nous avons trouvé que les parasites peuvent persister dans les kystes de leur hôte pour infecter une nouvelle génération l’année suivante. Référence du formulaire : ANR-FORM-090601-01-01 3/22 Un protiste peut avoir une morphologie remarquablement variable. La série en haut (1,2,3) montre la réabsorption des 'doigts' de Ceratium ranipes au coucher du soleil, un processus accompli en 3 heures. La série du bas (A,B,C) montre les types de coquilles formées par une seule espèce de cilié tintinnide. Ces organismes font 200 µm de longueur. Production scientifique. Les découvertes sont documentées dans des dizaines d'articles (39) au sein de revues scientifiques très sélectives et de 5 thèses. Outre des publications, le projet a produit des logiciels pour l'analyse des séquences d'ADN et la construction d'arbres phylogénétiques. Une galerie d'images de protistes planctoniques, une bibliothèque virtuelle des monographies taxonomiques et des guides pour l'identification des groupes spécifiques a été créée. Tous ces produits d'Aquaparadox ont été mis en accès libre via http://www.obs-vlfr.fr/LOV/aquaparadox/ Le projet AQUAPARADOX etait un projet de recherche fondamentale coordonné par John R. Dolan. Il a été réalisé par un consortium de 4 équipes: 1) Microbial Ecology and Biogeochemistry, Laboratoire d'Océanographie de Villefranche, Université Paris6 CNRS UMR 7093 (J. Dolan, R. Lemeé), 2) Microbial Diversity and Evolution, Ecologie, Systématique et Evolution, Université Paris-Sud XI CNRS UME 8079 (P. Lopez-Garcia, D. Moreira), 3) Diversity of Ocean Plankton, Adaptation et Diversité en Milieu Marin, Université Paris 6 CNRS UMR 7144 (L. Guillou, N. Simon), et 4) Virtual Biology Laboratory, Institute of Developmental Biology and Cancer, Université Nice- Sophia Antipolis CNRS UMR 6543 (R. Christen). Commencé en janvier 2008 et terminé en decembre 2011, le projet bénéficié d’une aide ANR Biodiversite de 497.000 € et d’une aide du Pôle Mer PACA de 21.000 €, pour un coût global estimé à 1,9M €. Référence du formulaire : ANR-FORM-090601-01-01 4/22 B.2 English Non-Technical Project Summary AQUAPARADOX: Why So Many Species in the Plankton? Examining Biodiversity in the Ocean. The microscopic plants and animals of the plankton are the base of the marine food chain. Among planktonic microbes, there seems to be an unreasonably large number of species, thousands in a single liter: 'the paradox of the plankton'. Protists of the plankton, single-celled organisms, are typical as species richness is high and each species appears to be very widely distributed. Arguably, we need to know what exists in the plankton to understand how marine food chains work and the effects of global change. We examined basic questions concerning protists of the plankton by studying particular groups typical of the different types: primary producers (plants), grazers (animals) and parasites. Are there really as many different species as there seems to be? Perhaps some species look different under different conditions. Is an organism found around the world really the same organism everywhere? Aquaparadox was a basic research project focused on protist biodiversity in the marine plankton. Probing the plankton using field sampling, laboratory cultures, and molecular analyses. We compared the structure of natural assemblages of plankton protists to those of the most abundant multi-cellular plankton, the copepods. We sought to determine if protists differed fundamentally from multicellular plankton. We compared the characteristics of natural communities of protists assemblages and copepod assemblages on different scales of time and space. In the laboratory, we examined the morphological variability of individuals grown from a single cell. We compared strains
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